linux-kernel - Re: [PATCH] mips: export icache_flush

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Date:	Sun, 23 Mar 2014 02:41:37 +0300
From:	Sergei Shtylyov <sergei.shtylyov@...entembedded.com>
To:	Kees Cook <keescook@...omium.org>
CC:	Paul Gortmaker <paul.gortmaker@...driver.com>,
	Ralf Baechle <ralf@...ux-mips.org>,
	Sanjay Lal <sanjayl@...asys.com>,
	John Crispin <blogic@...nwrt.org>, linux-mips@...ux-mips.org,
	LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] mips: export icache_flush_range

On 03/23/2014 12:05 AM, Kees Cook wrote:

>>>>> The lkdtm module performs tests against executable memory ranges, so
>>>>> it needs to flush the icache for proper behaviors. Other architectures
>>>>> already export this, so do the same for MIPS.

>>>>> Signed-off-by: Kees Cook <keescook@...omium.org>
>>>>> ---
>>>>> This is currently untested! I'm building a MIPS cross-compiler now...
>>>>> If someone can validate this fixes the build when lkdtm is a module,
>>>>> that would be appreciated. :)
>>>>> ---
>>>>>    arch/mips/mm/cache.c |    1 +
>>>>>    1 file changed, 1 insertion(+)

>>>>> diff --git a/arch/mips/mm/cache.c b/arch/mips/mm/cache.c
>>>>> index fde7e56d13fe..b3f1df13d9f6 100644
>>>>> --- a/arch/mips/mm/cache.c
>>>>> +++ b/arch/mips/mm/cache.c
>>>>> @@ -38,6 +38,7 @@ void (*__flush_kernel_vmap_range)(unsigned long vaddr,
>>>>> int
>>>>> size);
>>>>>    void (*__invalidate_kernel_vmap_range)(unsigned long vaddr, int size);
>>>>>
>>>>>    EXPORT_SYMBOL_GPL(__flush_kernel_vmap_range);
>>>>> +EXPORT_SYMBOL_GPL(flush_icache_range);

>>>>      Have you run this thru scripts/checkpatch.pl? It would have told you
>>>> that
>>>> an export should immediately follow the corresponding function body,
>>>> AFAIK.

>>>      Hm, it doesn't now but definitely used to...

>>     Decided to check Documentation/CodingStyle, and it still codifies this:

>> In source files, separate functions with one blank line.  If the function is
>> exported, the EXPORT* macro for it should follow immediately after the
>> closing
>> function brace line.  E.g.:

>> int system_is_up(void)
>> {
>>          return system_state == SYSTEM_RUNNING;
>> }
>> EXPORT_SYMBOL(system_is_up);

> Yup, thanks. I know the style, but it seemed from the source file that
> the style was to declare the function pointers in bulk, and then
> explicitly export them in the next section, so I continued that style.
> For example:

> void (*flush_cache_sigtramp)(unsigned long addr);
> void (*local_flush_data_cache_page)(void * addr);
> void (*flush_data_cache_page)(unsigned long addr);
> void (*flush_icache_all)(void);

> EXPORT_SYMBOL_GPL(local_flush_data_cache_page);
> EXPORT_SYMBOL(flush_data_cache_page);
> EXPORT_SYMBOL(flush_icache_all);

> Regardless, I'm happy to stick it in the middle of the function
> pointers if that's preferred.

    Ah, that's a variable! I didn't realize that. Looking into checkpatch.pl, 
it should warn about variables as well though... but it doesn't.

> -Kees

WBR, Sergei

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